Success! In Clinical Laboratory Science – Microbiology Practice Test

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• Rust-colored sputum in lobar pneumonia is most characteristic of infection with which organism?
• How long does Mycobacterium fortuitum take to grow on MacConkey agar?
• Which statement is true regarding Vibrio cholerae?
• Which organism is an etiologic agent of endocarditis?
• In a pregnant patient with fever and flu-like symptoms, a blood culture on SBA yields small, translucent beta-hemolytic colonies. Which organism is most likely the etiologic agent?
• Brucella spp. are which of the following?
• Which of the following is a fluorescent stain for mycobacteria?
• The organism associated with a disease characterized by a pseudomembrane in the throat and an exotoxin absorbed into the bloodstream with lethal effect is which species?
• Which test is treponemal-specific for syphilis?
• What indicator is commonly used to confirm that anaerobic conditions have been achieved in culture?
• Lack of motility is a characteristic of which genus?
• Which organism is inhibited by bile, produces a black pigment, and ferments glucose, sucrose, and lactose?
• The selective nature of Hektoen-enteric agar is due to the inclusion of which component?
• Bacteria producing clear colonies with black centers on Hektoen-enteric agar were isolated from a stool culture. Which of the following is true?
• Which organism is an etiologic agent of primary atypical pneumonia?
• Campylobacter jejuni is which of the following?
• Which trait characterizes most staphylococci and aids their isolation from clinical specimens?
• Which Mycobacterium species is nonchromogenic?
• After 72 hours of anaerobic incubation, small olive-green to black colonies are seen; a Gram stain reveals gram-positive cocci. Which organism is most likely?
• Which organism is a gram-negative bacillus among the listed choices?
• Severe disseminated intravascular coagulation often complicates septicemia caused by which organism?
• A middle-aged man with pneumonia, exposure to misted greens, and immunosuppression is most likely infected with which organism?
• Which genus is a gram-positive rod that is sometimes associated with pharyngitis?
• Which organism is the most common photochromogenic mycobacterium isolated in the United States?
• Which organism’s beta-hemolysis on blood agar is primarily due to streptolysin S?
• Listeria monocytogenes colonies on SBA plate most closely resemble colonies of which organism?
• In a semisolid medium containing resazurin, a pink color indicates which condition?
• The ethylhydrocupreine HCl susceptibility test is a presumptive test for the identification of which organism?
• The Microbial Identification MIDI system is based on which method?
• The method of serogrouping Shigella used in the clinical laboratory is based on which antigens?
• Which of the following describes Acinetobacter baumannii complex?
• Which clostridial species has a terminal spore that causes the cell to swell?
• Which antimicrobial agent is recommended for screening MRSA?
• In suspected EHEC infection, what is the recommended management regarding antibiotic therapy?
• SP4 Agar is the specialized medium used to culture which organism from clinical specimens?
• Which organism is the causative agent of Hansen disease?
• What range of CO2 is appropriate for capnophilic incubators?
• Prevotella melaninogenica can produce which pigment?
• Which statement is correct regarding blood cultures?
• The most common etiologic agent of community-acquired uncomplicated cystitis is which organism?
• Which disease is associated with the erythrogenic toxin produced by certain streptococci?
• Which of the following is a characteristic of Staphylococcus aureus?
• Haemophilus influenzae strains that produce beta-lactamase are resistant to which antibiotic?
• Which Mycoplasma species is cited as being grown on SP4 agar?
• Which organism outbreaks in hospital ICU settings are commonly linked to faucet aerators and humidifiers?
• Which organism is known for violet pigment production on colonies?
• A viridans streptococcus such as Streptococcus sanguis is most commonly linked to which condition?
• Which organism is most commonly associated with toxic shock syndrome in menstruating women?
• What peripheral smear finding is typical in HUS?
• Which Mycobacterium species is associated with livestock and is a zoonosis?
• In a child with meningitis and Gram-negative diplococci in CSF, what is the most likely etiologic agent?
• A genital specimen inoculated into 10 B broth shows an alkaline reaction after overnight incubation without turbidity. What is the most likely explanation?
• Erysipelas is most commonly caused by which organism?
• Reptiles kept as pets are commonly associated with transmission of which pathogen?
• The helicoidal, flexible organism seen in a blood smear with length of about 12 μm and semi-circular hooked ends corresponds most closely to which genus?
• The soil inhabitant Streptomyces is associated with which condition?
• Aggregatibacter aphrophilus endocarditis is most likely sourced from which site?
• Which organism is commonly involved in freshwater wound infections and is a Gram-negative rod?
• Which other species of Mycobacterium is able to demonstrate growth on MacConkey agar in 5 days?
• Which of the following nonfermenters is rarely isolated in the United States?
• Which statement about Campylobacter jejuni is true?
• Which of the following mycobacteria has an optimal growth temperature 30-32°C?
• Which test is used in vitro to detect toxigenic strains of Corynebacterium diphtheriae?
• Besides Pseudomonas aeruginosa, which organism is an important cause of lower respiratory tract infections in patients with cystic fibrosis?
• Which of the following is an occasional cause of respiratory tract infections and is rapidly urea positive?
• Which of the following is considered a zoonotic disease?
• The Mycobacterium that is the etiologic agent of 'swimming pool granuloma' is?
• An aerobic, filamentous, branching gram-positive organism that stains weakly acid-fast in a brain abscess from an immunosuppressed patient is most likely which genus?
• Chancroid is a sexually transmitted infection characterized by genital ulcers and tender inguinal lymphadenopathy. Which organism is classically associated with chancroid pathology?
• Which organism is catalase-negative and capable of growth in bile-esculin and 6.5% NaCl?
• How can Kingella denitrificans be differentiated from Neisseria gonorrhoeae?
• Which mycobacterium is described as rapidly growing and grows on MacConkey agar in 5 days?
• Violet-colored colonies are typically produced by which organism?
• Why are cultures for Gardnerella vaginalis not routinely recommended in clinical microbiology?
• The gram-negative, anaerobic bacillus frequently implicated in serious infections such as brain and lung abscesses is which organism?
• Infection of the gastric mucosa leading to gastritis or peptic ulcers is most commonly associated with which organism?
• Which Vibrio cholerae serogroup is linked to epidemic disease due to toxigenic strains?
• A purulent joint aspirate Gram stain shows polymorphonuclear cells with intracellular and extracellular gram-negative diplococci. Which organism is most likely responsible?
• Which organism is a likely causative agent in aspiration pneumonia?
• Which organism is commonly part of vaginal flora and may appear as small alpha-hemolytic colonies on SBA after extended incubation?
• The etiologic agent of epidemic relapsing fever is Borrelia recurrentis. It is commonly transmitted by which vector?
• Which statement is true of Brucella?
• A catalase-negative gram-positive coccus is isolated from a urine sample of a hospitalized patient. The bacterium produced a black pigment on bile-esculin agar and formed acid from glucose in the presence of 6.5% NaCl. What is the most likely identification?
• Which genus is most associated with identification by the porphyrin test?
• Which Bacillus species is nonmotile?
• Which organism forms pale pink colonies and is pathogenic for animals including swine and horses?
• Cardiobacterium hominis has been recovered from endocarditis. Which identifying characteristic is true?
• Which organism is CAMP test positive, according to the material?
• Which statement is correct about Clostridium tetani?
• Which organism is commonly recovered from blood cultures in systemic infections and is associated with laboratory-acquired risk?
• Clavulanic acid is classified as which type of agent?
• The potentially lethal intoxication type of food poisoning often associated with improperly canned food is caused by which organism?
• The symptom of diffuse, watery diarrhea that produces a relatively clear stool containing mucus flecks is suggestive of infection caused by which organism?
• Gas gangrene is most commonly associated with which organism?
• A patient develops septicemia and hemorrhagic bullous skin lesions after eating raw oysters. Which organism is most likely responsible?
• The axial fibrils of spirochetes most closely resemble which bacterial structure?
• A suspension of the test organism for broth dilution and disk diffusion testing is adjusted to match the turbidity of which McFarland standard?
• Which organism is the most common indicator of bacterial vaginosis?
• Which Mycobacterium species is recommended to incubate skin cultures for recovery at 30°C?
• Which of the following diseases is most likely to be acquired from a hot tub or whirlpool?
• Neisseria lactamica closely resembles Neisseria meningitidis but can be differentiated from it by its ability to metabolize which sugar?
• Fried egg colonies are characteristic of which organism?
• Food poisoning with rapid onset of vomiting about 2 hours after eating, with no fever, is most likely due to which organism?
• Purulent material from a cerebral abscess showed Gram-positive cocci in chains and Gram-negative bacilli with pointed ends; aerobically incubated plates showed no growth at 24 hours. Most likely presumptive identification of the anaerobic agents?
• Which statement is true about mycoplasmas?
• Which statement about Clostridium botulinum is true?
• Which statement about Mycobacterium leprae is true?
• Acinetobacter sp. infections are most characteristically associated with which setting or condition?
• Small alpha-hemolytic colonies on a sheep blood agar plate after 48 hours of incubation from a vaginal culture describe which organism?
• Which organism cannot grow on MacConkey agar?
• Which population group is at higher risk for severe Legionella disease?
• Milk-associated transmission of cattle diseases includes which condition?
• Which organism is appropriate as a positive control in the PYR test?
• Which drug is active against parasitic infections and has importance for diseases caused by anaerobic bacteria?
• Which species is hippurate hydrolysis positive among the listed organisms?
• The causative agent of melioidosis is
• Which organism will turn a dark purple when tetramethyl-p-phenylenediamine hydrochloride is applied?
• Which of the following is correct for Aeromonas hydrophila complex?
• Which organism is commonly associated with wound infections?
• The Campylobacter species noted to produce septicemia, septic arthritis, meningitis, jaundice with hepatomegaly, and thrombophlebitis in debilitated patients is which?
• For rapid diagnosis of Legionella in hospitalized patients, which test is commonly used?
• Which organism is commonly diagnosed by serology for infections?
• For the disk diffusion testing of Haemophilus influenzae, the recommended medium is Mueller-Hinton base supplemented with which components?
• Vibrio vulnificus is a well-established human pathogen that is known to cause which type of infection?
• Which enzymatic property is true for Acinetobacter baumannii?
• Outbreaks in ICUs associated with faucet aerators and humidifiers commonly involve which microorganism?
• Which organism is most commonly recovered in gas gangrene?
• Which member of the Enterobacteriaceae is oxidase positive?
• Kingella kingae is most noted for causing which infection, particularly in children?
• When performing the oxidase test, which statement would be appropriate?
• Which of the following media is both selective and differential?
• Stool culture shows gram-negative bacilli that are oxidase negative, citrate negative, indole negative; urease and ONPG positive; acid/acid in TSI w/o gas or H2S; which organism?
• The species of Mycobacterium that is most commonly associated with contamination of hot water systems in large institutions such as hospitals is which?
• The term for interactions where the combined effect is greater than the sum of individual effects is:
• Which genus is most likely to yield tan colonies that are tributyrin hydrolysis positive in a sputum culture?
• Which genus is associated with melioidosis and has a species that is the causative agent in that disease?
• The organism whose isolation can be hindered by fatty acids present in clinical specimens is which?
• Which organism is most closely associated with bacterial vaginosis among the listed organisms?
• Campylobacter spp. are associated most frequently with cases of
• Tobramycin is classified as which type of antimicrobial?
• Which organism produces a potent enterotoxin associated with severe diarrhea in outbreaks?
• Which Mycobacterium appears as buff-colored colonies after exposure to light and is niacin positive?
• Listeria monocytogenes infections are commonly linked to which foods?
• Which Mycobacterium produces an orange pigment and is most commonly recovered from water?
• The organism most commonly isolated in community-acquired uncomplicated cystitis is which?
• Eikenella corrodens is opportunistic, but it is most noted for causing which type of infections?
• Which organism is the etiologic agent of swimming pool granuloma?
• Which organism is a common member of the normal biota of the upper respiratory tract?
• Which statement about Neisseria gonorrhoeae is true?
• What is the optimal clinical specimen for the recovery of Legionella pneumophila?
• Which clinical features are commonly associated with Legionella infection?
• A tissue Gram stain shows Gram-positive bacilli with central spores; after 24 hours, there is no growth on aerobic culture or on chocolate agar incubated with increased CO2. Which genus is most likely involved?
• Which medium should be used for in vitro susceptibility testing of Streptococcus pneumoniae?
• Which statement is true for diagnosing Bordetella pertussis infection?
• Which organism among the following is catalase negative?
• Which medium is recommended by CLSI for routine susceptibility testing of nonfastidious bacteria?
• Shigella serogrouping relies on which surface antigen?
• Which organism would produce a yellow slant and yellow butt on TSI agar after incubating 18 hours?
• Haemophilus ducreyi is the causative agent of which disease?
• Susceptibility to thiophene-2-carboxylic acid hydrazide (T2H) is characteristic of which of the following mycobacteria?
• The classic toxigenic strains of which serogroup are implicated in epidemic infections of Vibrio cholerae?
• Acinetobacter baumannii has which characteristic?
• The vaccine for Haemophilus influenzae type b targets which serotype?
• What is the recommended adult blood culture volume per culture?
• Viridans streptococci are commonly part of the normal flora of which site?
• Pleomorphic gram-positive bacilli in a Gram stain best describes which organism?
• This bacterium, pathogenic for swine, horses, and cattle, is also known to cause disease in compromised human hosts. When grown on culture media, it produces pale pink colonies that help to presumptively identify it as
• Aerococcus species are noted for causing urinary tract infections and which cardiac infection?
• Erythromycin belongs to which antibiotic class?
• Which of the following is an important virulence factor of Bacteroides fragilis?
• Which organism is associated with both mercury droplet colony morphology and the agent of pertussis?
• Which statement about Shigella sonnei is true?
• An anaerobically incubated blood agar plate shows colonies surrounded by an inner zone of complete red cell lysis and an outer zone of incomplete cell lysis (double zone of beta-hemolysis). The most likely presumptive identification of this isolate would be which organism?
• The clinical syndrome described as severe, tender erythema with epidermal separation in an infant is most consistent with infection by which organism?
• A gram-negative kidney bean cellular morphology is a distinguishing characteristic of which organism?
• Infections with which species are usually acquired by the respiratory route?
• Which beta-lactam antibiotic class has the broadest spectrum?
• Donovan bodies in a groin lymph node biopsy indicate infection with a pathogen that...
• Swimmer's ear, a form of external otitis, is most commonly caused by which organism?
• Which organism produces a positive phenylalanine deaminase reaction?
• Tellurite reduction is used for presumptive identification of which organism?
• Which of the following is characteristic of Mycobacterium kansasii?
• Which organism is commonly associated with infections caused by invasive medical devices such as catheters or ventilators?
• Which organism is described as a fluorescent stain for mycobacteria?
• Which organism causes granulomatous skin lesions after aquarium or fish tank exposure?
• Donovan bodies are associated with donovanosis; the causative organism cannot be cultured on routine media. Which organism is this?
• A urine culture from a young woman grew a catalase-positive gram-positive coccus. The most likely organism is which?
• Which antimicrobial agent acts by inhibiting protein synthesis?
• Which Mycoplasmataceae has not been connected with human genital infections?
• During the first week of leptospirosis, the most reliable way to detect the presence of the causative agent is by the direct examination of which specimen?
• Cultures from the posterior pharynx are most commonly submitted to detect which organism?
• The quality of an expectorated sputum is evaluated based on which criterion?
• The porphyrin test determines an organism's requirement for which growth factor?
• Which of the following is true regarding spirochetes?
• A purulent aspirate of joint fluid from a 28-year-old female with joint pain showed many polymorphonuclear cells with intracellular and extracellular gram-negative diplococci. The appropriate selective medium for primary isolation would be
• Nonpathogenic Neisseria species are commonly part of normal microbiota of which region in healthy individuals?
• Streptococcus sanguis, a viridans streptococcus, is most commonly associated with which clinical condition?
• Loeffler's serum medium is recommended for the cultivation of which organism?
• Legionella pneumonia commonly presents with which radiographic pattern?
• Which organism is associated with infections in humans often linked to deli meats and improperly pasteurized dairy products?
• Which Treponema pallidum subspecies is associated with congenital infections?
• Scarlet fever is associated with which toxin or toxin-producing organism?
• Escherichia coli O157:H7 outbreaks are most commonly linked to which animal reservoir?
• What is the generally recommended digestion and decontamination method for processing clinical specimens for recovery of Mycobacterium tuberculosis?
• Generally, vancomycin is active against gram-positive bacteria. However, which of the following is more likely to exhibit resistance?
• The recommended medium for recovery of Mycoplasma pneumoniae from clinical specimens is
• Which genus is a Gram-positive bacillus with central spores commonly discussed in anaerobic infection contexts?
• Among beta-lactams, which class is described as having the broadest spectrum and includes agents like imipenem and meropenem?
• Which organism is most likely to be isolated in cultures from the anterior nares of healthcare workers?
• Endemic typhus is caused by which Rickettsia species?
• The most common photochromogenic Mycobacterium isolated in the United States is
• Which organism is most closely associated with gastric cancer?
• Which statement about Pasteurella multocida is true?
• Colonies said to have the appearance of a 'fried egg' are characteristic of
• Continuous blood culture systems that detect changes in headspace pressure in bottles are referred to as
• A gram-negative bacillus recovered from a child’s urine with recurrent UTIs is oxidase negative, lactose negative, urease positive, and motile. Most likely identification?
• Transfusion with refrigerated blood resulted in endotoxic shock; which organism likely involved?
• Which soil-dwelling genus is linked to actinomycotic mycetoma?
• Which medium is selective for Vibrio species due to its composition of bile salts and sucrose?
• Mycobacteria can be examined by using which stain?
• Production of a yellow pigment on nutrient or sheep blood agar is characteristic of which member of the Enterobacteriaceae?
• New York City agar was developed for the isolation of which organism?
• Which test is most appropriate for the presumptive identification of Prevotella melaninogenica?
• A test for the hydrolysis of esculin in the presence of bile is especially useful in identifying species of which genus?
• Which organism is the etiologic agent of erysipelas?
• Impetigo is commonly caused by which organism?
• Cronobacter spp. have frequently been linked to which of the following?
• Which statement is not true of Coxiella burnetii?
• Which adverse effect of chloramphenicol significantly limits its clinical usefulness?
• Edwardsiella tarda is occasionally isolated in stool specimens and can biochemically be confused with which organism?
• Which statement best describes Bacteroides fragilis?
• The finding of five to six acid-fast bacilli per field in a carbol fuchsin smear of expectorated sputum should be reported as
• The etiologic agent of whooping cough is
• A fermentative gram-negative bacillus that is oxidase positive, motile, and grows well on MacConkey agar is which species?
• A nonlactose fermenter is isolated from a stool specimen. A biochemical multitest assay identifies the isolate as Shigella sp. Subsequently, the isolate demonstrates agglutination in Shigella group B antisera. Which of the following is most likely?
• A positive Voges-Proskauer reaction is characteristic of which organism?
• Which microorganism will grow only on culture media supplemented with either cysteine or cystine?
• For the selective isolation of Vibrio spp., the recommended agar is which?
• Shigella sonnei is differentiated from other Shigella species by which test?
• Kanamycin-vancomycin laked-blood (KVLB) agar incubated anaerobically is primarily used for isolation of which organism?
• Coagulase production by Staphylococcus aureus converts fibrinogen to what?
• Which test is most appropriate for presumptive identification of Clostridioides (Clostridium) difficile isolates?
• Salmonella Typhi exhibits a characteristic biochemical pattern differentiating it from other salmonellae. Which of the following is characteristic of S. Typhi?
• Disinfectants such as povidone iodine prep pads have been recalled due to contamination. Which organism is most likely to be isolated in such cases?
• A branching, gram-positive rod that is weakly acid-fast and can cause brain abscesses in immunocompromised hosts belongs to which genus?
• The sexually acquired disease characterized by genital ulcers and tender inguinal lymphadenopathy, which is caused by a small, gram-negative bacillus, is known as
• Which genus is typically nonmotile among the Enterobacterales?
• On Gram stain, a morphology that resembles 'seagull wings' is most characteristic of which organism?
• Which antibiotic is bactericidal?
• The phenomenon of bacterial resistance to the bactericidal activity of penicillins and cephalosporins, with only inhibition of growth, is known as which term?
• Chlamydophila psittaci infections in humans most commonly result after exposure to
• The characteristic colony morphology of Actinomyces israelii on solid agar resembles which of the following?
• The novobiocin susceptibility test is used for the identification of which organism?
• Solubility in the presence of sodium deoxycholate is characteristic of which organism?
• The "nonpathogenic" Neisseria spp. are generally regarded as normal microbiota of which site?
• A negative PYR test is demonstrated by which organism?
• In the catalase test, the formation of bubbles is due to
• An example of a halophilic microorganism is which of the following?
• The pulmonary form of anthrax is known as which name?
• Infant botulism was confirmed by demonstration of toxin in the stool. The child most likely contracted this disease by which route?
• During childbearing years, the normal vaginal biota is predominantly which organism?
• Which Vibrio species is closely associated with rapidly progressing wound infections in patients with underlying liver disease?
• Egg yolk agar showing a precipitate around the colony indicates which activity?
• Which organism grows on MacConkey agar and is often implicated in nosocomial infections?
• Which Neisseria species produces acid from glucose but not from maltose, lactose, or sucrose?
• Which organism is an important cause of food poisoning?
• Rocky Mountain spotted fever is transmitted by the bite of a tick infected with which Rickettsia species?
• Penicillin exerts its antibacterial effect by which mechanism?
• Chronic carriers are typically associated with dissemination of which organism?
• An organism occasionally misidentified as an enteric pathogen because some isolates produce H2S is
• For screening enterohemorrhagic E. coli in stool, which medium is best?
• For nonspecific staining of Rickettsia, which stain is recommended?
• Ethylhydrocupreine HCl susceptibility test is a presumptive identification test for which organism?
• For an epidemiologic survey of upper respiratory tract carriers of Neisseria meningitidis or Bordetella pertussis, what is the optimal specimen for culture?
• Which bacterium is part of the normal vaginal biota that helps resist the onset of bacterial vaginosis?
• Which test would be appropriate in the diagnosis of a mycobacterial infection?
• Streptococci are unable to synthesize which enzyme?
• Which genus is a notable cause of lower respiratory tract infections in cystic fibrosis patients besides Pseudomonas aeruginosa?
• Which organism listed is a gram-negative bacillus?
• The etiologic agent of epidemic typhus in the material is which Rickettsia species?
• In immunocompromised hospitalized patients, which organism is an aerobic gram-positive rod known to cause bacteremia?
• Which toxin is the most potent bacterial exotoxin known?
• Which statement is characteristic of Eikenella corrodens?
• Which factor is most commonly associated with laboratory-related infections?
• The Gram stain morphology described as 'seagull wings' is associated with which organism?
• Which nonfermenting organism is historically associated with glanders?
• A cerebrospinal fluid sample from an infant suspected of meningitis shows Gram stain; after 24 hours, small tan colonies grow on chocolate agar incubated in CO2, while sheep blood agar incubated in CO2 shows no growth. Which organism is most likely?
• Which organism is the etiologic agent of Lyme disease?
• Which statement about gamma-interferon release assays for diagnosing tuberculosis is true?
• Which class inhibits folic acid synthesis in bacteria by targeting dihydropteroate synthase?
• Which organism is primarily used for isolation on KVLB agar in anaerobic culture?
• Which combination of organisms is most likely in a polymicrobial brain abscess?
• To ensure anaerobic conditions in jars or chambers, which oxygen-sensitive indicator is used?
• Eikenella corrodens is best known for causing infections in which site?
• Which genus is typically nonmotile among common gram-negative enteric bacteria?
• Which organism's isolation is enhanced by incubation in increased CO2?
• Which exposure is strongly associated with Legionella infection?
• Which of the following is true about Chlamydophila pneumoniae?
• Which organism is known for kidney-bean shaped cells on microscopic examination?
• What is the optimal specimen type for recovering Bordetella pertussis?
• Legionella pneumophila is the etiologic agent of both Legionnaires disease and which condition?
• Milk historically has been the primary food associated with transmission of which disease in cattle-human transmission?
• Rust-colored sputum is a classic clue for pneumonia caused by which organism?
• A 21-year-old sexually active woman with urinary symptoms and a lactose-fermenting gram-negative rod in culture most likely etiologic agent is
• Adventure racers contracted illness after contact with water and soil; most likely etiologic agent?
• Mobiluncus, a genus associated with polymicrobial vaginal infections, is most closely linked to which condition?
• Yersinia pseudotuberculosis commonly manifests as which clinical condition?
• Rapid testing for beta-lactamase production is recommended before initiation of antimicrobial therapy for isolates of which organism?
• Which Fusobacterium species is most frequently isolated from clinical infections?
• Which agar medium is claimed to ease isolation of Neisseria gonorrhoeae from contaminated specimens?
• Which organism is most commonly associated with opportunistic Bacillus infections such as bacteremia and endocarditis?
• Growth in a 48-hour semisolid agar stab culture at room temperature reveals lateral filamentous growth away from the stab near the top of the medium. This observation is most characteristic of which organism?
• A young woman with fever, vomiting, diarrhea, rash and vaginal culture with many coagulase-positive staphylococci; what diagnosis?
• Which organism is catalase positive, helping differentiate it from Actinomyces?
• Silver-stained skin lesion with spirochetes and systemic symptoms in the northeastern United States; which disease is diagnosed?
• In the decontamination and digestion procedure for the isolation of mycobacteria from sputum samples, what is the role of NALC?
• Erysipeloid is a disease typically caused by which organism?
• A gram-positive coccus that is catalase positive, lysostaphin resistant, and modified oxidase positive is best identified as a member of which genus?
• Traveler's diarrhea is commonly associated with which etiologic agent?
• The extended-spectrum beta-lactamases confer resistance to which antibiotic?
• Which organism is the causative agent of a malignant pustule?
• Which organism is associated with serious congenital infections?
• The MIDI system identifies microbes by analyzing which data?
• Which statement correctly identifies the rapid beta-lactamase test use?
• Which organism is associated with hemolytic uremic syndrome as a complication after infection?
• What is the common method for confirmation of Chlamydia trachomatis in sexually transmitted infections?
• Which test would be used for presumptive identification of Prevotella melaninogenica?
• Which organism is a Gram-positive rod known to cause meningitis in neonates and immunocompromised adults and can grow at refrigeration temperatures?
• All members of the Pseudomonas fluorescens group are noted for producing which pigment?
• A teenage patient with pneumonia presents with Gram-positive rods that are CAMP-positive and catalase-negative after culture. Which organism is most likely?
• Colonies of Neisseria species turn color when a redox reagent is applied. The color change is indicative of the activity of which bacterial enzyme?
• Male with non-healing cutaneous granulomatous lesions after aquarium exposure; most likely etiologic agent?
• Which trait is commonly used to isolate staphylococci from clinical specimens?
• The beta-hemolysis produced by group A Streptococcus seen on blood agar incubated aerobically is primarily the result of which streptolysin?
• Which organism is most likely to be isolated in cultures from the anterior nares of healthcare workers?
• In Shiga toxin–producing E. coli infections, which toxin is associated with severe disease and HUS?
• During the first week of leptospirosis, the most reliable direct detection method is examination of which specimen?
• Which organism requires cysteine or cystine for growth and is commonly tested in clinical labs?
• Cefsulodin-irgasan-novobiocin (CIN) agar is recommended for the recovery of which organism?
• Bacillus cereus has been implicated as the etiologic agent in which condition?
• The halophilic organism among the listed options is which?
• The description of "Medusa head" colonies on solid agar is most characteristic of which organism?
• Which Bacillus species is nonmotile?
• Which organism is a nonspore-forming, gram-positive, anaerobic bacillus?
• Which of the following would be appropriate for positive and negative controls in the PYR test?
• A gram-positive rod sometimes associated with pharyngitis is which organism?
• Cystine-tellurite blood agar plates are recommended for isolation of which organism?
• Endogenous oral flora is the likely source of infection for which organism causing endocarditis?
• The production of H2S is one characteristic used to differentiate which of the aerobic gram-positive bacilli?
• Borrelia burgdorferi is the etiologic agent of which disease?
• When performing an oxidase test, which statement is correct?
• Which statement is true regarding Clostridium perfringens?
• Which statement best describes the habitat of clinically significant clostridia?
• The etiologic agent of the majority of adult joint infections is which organism?
• Which statement about Neisseria gonorrhoeae is true?
• Which specimen type is the preferred specimen for Bordetella pertussis detection?
• Streptococci obtain energy primarily by fermenting sugars to which acid?
• Which antibiotic is a macrolide?
• Fecal cultures are inoculated on thiosulfate-citrate-bile salts-sucrose agar specifically for isolation of which organism?
• Agglutination in Vi grouping serum is a diagnostic feature used to identify which serovar of Salmonella?
• Heating an unheated suspension of Salmonella Typhi typically produces agglutination of Vi antisera. After heating, agglutination will occur in which grouping sera?
• In capnophilic incubators, carbon dioxide should be maintained between which ranges?
• The pH of the agar used for the Kirby-Bauer test should be within which range?
• In suspected cases of brucellosis, what is the most sensitive specimen to submit for culture?
• Buffered charcoal yeast extract agar is primarily used for recovering which organism?
• The description of "Medusa head" colonies on solid agar is most characteristic of which organism?
• The causative agent of the septicemic, hemolytic disease known as Oroya fever is which organism?
• Which of the following organisms is unable to grow on MacConkey agar?
• Obligate anaerobic, gram-negative bacilli recovered from an abdominal wound showed resistance to penicillin and growth not inhibited by bile. Which organism is most likely?
• Which body site is normally colonized by normal microbiota?
• Which statement accurately describes clostridia?
• Ixodes dammini is a tick vector for which pathogen in the northeastern United States?
• Colonies described as resembling droplets of mercury are characteristic of which organism?
• Edwardsiella tarda in stool can be biochemically mistaked for which organism?
• Which statement best describes toxin production in Clostridium perfringens?
• Buffered charcoal yeast extract agar is the recommended medium for the recovery of which organism?
• In oxidase testing, the observation of a purple color after about one minute indicates what?
• Which organism is most commonly associated with gastritis or peptic ulcers?
• In a sinus culture, small pinpoint colonies growing around medium white colonies on sheep blood agar are most likely which organism?
• Which specimen is routinely decontaminated when trying to recover Mycobacterium species?
• Which selective medium is used for primary isolation of Neisseria species, including Neisseria gonorrhoeae, from clinical specimens?
• Which test serves as a screening method for enterohemorrhagic E. coli by detecting beta-glucuronidase activity?
• Transmission of the sylvatic form of typhus infection caused by Rickettsia prowazekii is associated with which animal?
• Isolation of Neisseria gonorrhoeae requires incubation under which condition?
• Most common cause of pneumonia in elderly patients
• Chancroid is caused by which organism?
• Staphylococcus saprophyticus is a recognized pathogen most commonly associated with which infection?
• Which statement is true of Bacteroides fragilis?
• Initial infections in women with this organism are often asymptomatic.
• Which Mycobacterium species is most commonly associated with disseminated disease in HIV/AIDS patients?
• A physician orders a urea breath test; she must suspect an infection caused by which organism?
• Which Pasteurella species is associated with human infections following cat bites?
• Kingella kingae is most notable for bone and joint infections in which population?
• The slowly growing, orange-pigmented acid-fast bacillus associated with pediatric cervical lymphadenitis is most likely which species?
• The majority of gram-positive, nonspore-forming, anaerobic bacilli isolated from clinical material are most likely which species?
• Listeria monocytogenes colonies on SBA plate most closely resemble colonies of which organism?
• The K antigen of the family Enterobacteriaceae is
• Which organism is a spirochete transmitted by contaminated water and can cause severe illness?
• Which genus comprises intracellular pathogens that are notable causes of zoonotic infections?
• Chlamydia trachomatis causes which of the following?
• A 36-year-old man returning from India with suspected typhoid fever; what is the most critical laboratory test to establish or rule out the diagnosis?
• The enterotoxins of both Vibrio cholerae O1 and toxigenic strains of Escherichia coli produce serious diarrhea by what mechanism?
• A medium named after a city is used for the isolation of Neisseria gonorrhoeae. Which medium is it?
• A 7-year-old girl develops bloody diarrhea and later hemolytic uremic syndrome after visiting a petting zoo with calves, lambs, and chickens. Which etiologic agent is most likely?
• What is the most common etiologic agent of infections associated with prosthetic devices such as artificial heart valves and CSF shunts?
• A causative agent of the form of conjunctivitis known as pinkeye is which organism?
• In a sputum specimen from suspected lobar pneumonia showing many white blood cells and gram-positive cocci primarily in pairs, which test should be performed on the culture isolate?
• An important characteristic of Neisseria gonorrhoeae or the infection it produces is
• Growth of the organism in the presence of bile supports identification as which organism in this scenario?
• What is the predominant indigenous biota of the colon?
• Which Bacillus species is most commonly isolated in opportunistic infections such as bacteremia and endocarditis?
• Which statement is true regarding serologic tests for diagnosing syphilis?
• The in vitro test that detects diphtheria toxin production by precipitating toxin and antitoxin in agar gels is known as the?
• The agar used in Kirby-Bauer testing should have a pH in which range?
• The flattened adjacent sides of the cellular appearance of which microorganism are said to resemble kidney beans?
• Which Neisseria species produces acid from glucose and maltose but not sucrose or lactose?
• Chlamydophila psittaci is most commonly associated with exposure to which reservoir?
• Pus aspirated from an empyema showed Gram-negative bacilli and colonies producing a soluble green pigment; the most likely organism is?
• Which organism is most commonly associated with gastric ulcers and gastric cancer?
• In MALDI-TOF mass spectrometry, how are biomolecules separated?
• A urinary tract infection in a young woman is most often caused by which catalase-positive gram-positive cocci?
• Erythromycin eye drops are routinely administered to infants to prevent infections caused by which organism?
• A positive VDRL test for syphilis in a patient with hepatitis and no partner history: what is the appropriate next step?
• Hemolytic uremic syndrome is classically characterized by which triad?
• What is the recommended anticoagulant for body fluids that may clot sent for microbiologic examination?
• Which one of the following microorganisms cannot be cultivated on artificial cell-free media?
• How is human infection with the causative agent of Q fever most commonly acquired?
• Among the toxigenic types of Clostridium botulinum, which types are associated with human botulism?
• Which organism is commonly associated with urinary tract infections in children and is urease positive?
• Skin cultures for the recovery of Mycobacterium spp. should be incubated at
• In the described case, which medium and atmosphere supported growth of the organism?
• Which organism is most commonly associated with acne and is a gram-positive, nonspore-forming anaerobe?
• Which agent is classified as a beta-lactamase inhibitor?
• Which medium is used to selectively isolate Yersinia enterocolitica from clinical specimens?
• Exfoliatin produced by Staphylococcus aureus is responsible for causing which condition?
• Which pigment is produced by the Pseudomonas fluorescens group?
• The most common etiologic agent of infections associated with prosthetic devices such as artificial heart valves and CSF shunts is which organism?
• Which organism is described as intracellular pathogens in humans?
• The slowly growing, orange-pigmented acid-fast bacillus isolated from cervical lymph nodes in a child with cervical adenitis is most likely which species?
• The medium recommended for routine susceptibility testing of nonfastidious bacteria is:
• Which organism hydrolyzes sodium hippurate to benzoic acid and glycine?
• For suspected brucellosis, which specimen yields the highest culture sensitivity?
• Indole production is a positive test for which organism?
• Which organism is a likely cause of aspiration pneumonia among the choices?
• The fermentative agent that may infect reptiles and fish as well as humans when exposed to contaminated soil or water is which genus?
• Legionella pneumophila infections are most often acquired from which sources?
• For the detection or recovery of mycoplasmata, which statement is true?
• In MALDI-TOF mass spectrometry, what does the TOF in the acronym stand for?
• A test that could be used to screen for enterohemorrhagic E. coli
• Blood cultures are recommended for recovery of which organism?
• The mild type of typhus fever that is caused by recrudescence of an initial attack of epidemic typhus is known as which disease?
• Chronic carriers are typically associated with dissemination of which organism?
• Corneal scrapings are useful for the diagnosis of infection caused by
• A curved appearance on Gram stain is characteristic of which organism?
• Which organism is the etiologic agent of a hemorrhagic fever disease occurring in the Andes region of South America?
• The biochemical profile lactose negative, citrate negative, urease negative, lysine decarboxylase negative, nonmotile best describes which organism?
• Which organism is oxidase-positive and considered a nonfermenter and is a common cause of opportunistic infections?
• The causative agent of endemic or murine typhus is which of the following Rickettsia species?
• Hippurate hydrolysis test is most helpful in differentiating which group of organisms?
• Pyocyanin pigment is characteristically produced by which organism?
• Which organism is identified by a test for esculin hydrolysis in the presence of bile?
• To maximize recovery of Staphylococcus aureus from a stool sample, the primary plating medium should include which selective agent?
• In the modified carbapenem inactivation method (mCIM) assay, which result indicates carbapenemase production by the test organism?
• The majority of clinical isolates of Klebsiella are which species?
• Campylobacter jejuni is best described as which morphological form?
• Which statement about Mycobacterium leprae is NOT true?
• Which organism is the etiologic agent of Pontiac fever?
• A filamentous gram-positive rod recovered from an aspirate of a closed chest abscess grew only under anaerobic conditions and was not acid-fast. What is the most likely identification?
• Actinomyces israelii is best described as which type of organism?
• Which organism produces the pigment pyocyanin?
• Abiotrophia was formerly known as nutritionally variant streptococci and requires growth factors, specifically which one?
• Which organism is frequently misidentified as an enteric pathogen because some isolates produce hydrogen sulfide, leading to confusion in identification?
• DNA-amplification techniques are used to confirm infection with which pathogen?
• Which of the following is true of Haemophilus spp.?
• Which culture method helps differentiate Escherichia coli O157:H7 from non-O157 strains due to its effect on sorbitol fermentation?
• Malignant pustule is a hallmark of infection with which bacterium?
• Enterococcus faecium is characteristically
• Egg yolk agar precipitation around colonies indicates production of which enzyme?
• The majority of cases of laboratory-related infections are associated with which factor?
• Septicemia caused by which organism is commonly associated with underlying malignancy?
• The minimum bactericidal concentration (MBC) is defined as the lowest concentration that kills at least what percent of the original inoculum?
• Which organism is most commonly linked to gastroenteritis and is associated with Campylobacter infections?
• Nocardia brasiliensis infections in humans characteristically produce which feature?
• On Tinsdale agar, Corynebacterium diphtheriae colonies are described as which of the following?
• The etiologic agent of Hansen disease is which Mycobacterium?
• A sputum culture yields moderate growth of gram-negative diplococci forming tan colonies that are tributyrin hydrolysis positive. Which genus is most likely?
• Abiotrophia, formerly known as nutritionally variant streptococci, will not grow on routine blood or chocolate agars because they are deficient in which growth factor?
• Haemophilus aegyptius requires which factors?
• Resistance to clindamycin can be induced in vitro by exposure to which antibiotic?
• Which test is most appropriate for presumptive identification of Peptostreptococcus anaerobius?
• Cronobacter sakazakii is notable among Enterobacteriaceae for producing which pigment on media?
• Which organism is most commonly associated with double-zone beta-hemolysis on blood agar?
• Which Mycobacterium is most noted for being associated with patients with AIDS?
• Which organism is commonly associated with pinkeye conjunctivitis?
• The diagnosis of pseudomembranous colitis, Clostridioides difficile-associated disease, is often made by which method?
• Which organism is typically optochin sensitive, aiding identification of Streptococcus pneumoniae?
• Which statement correctly identifies a mechanism of action for sulfonamides?
• Which age group is most commonly affected by EHEC outbreaks that lead to HUS?
• A cervical mucosal abscess grew an anaerobic gram-negative bacillus that was inhibited by bile, produced a black pigment, and was negative for indole production but positive for glucose, sucrose, and lactose fermentation. This isolate would most likely be which species?
• Which statement best describes the Gram stain appearance of Legionella in respiratory specimens?
• Mycobacteria have a large amount of a component in their cell wall that other bacteria lack. That component is which?
• The oxidase test is used to identify bacteria of which genus, indicated by a positive reaction?
• Which organism is described as obligate anaerobic gram-positive cocci?
• Detection of antibody against cardiolipin is useful for the diagnosis of which disease?
• Which organism is commonly found in the mouth and upper respiratory tract of humans?
• Listeria monocytogenes is characteristically positive for which test?
• The etiologic agent most commonly associated with septicemia and meningitis of newborns is which organism?
• The Haemophilus influenzae vaccine protects against which serotype?
• Which organism has a negative oxidase test?
• It is generally most appropriate to perform a hippurate hydrolysis test to aid in the identification of
• Which genus is most likely the yellow, nonfermentative gram-negative bacillus isolated from nebulizers?
• Nocardia can be differentiated from Actinomyces based on
• Ampicillin resistance in Haemophilus influenzae is due to production of what enzyme?
• An aerobic gram-positive rod known to cause bacteremia in hospitalized, patients who are immunocompromised is which organism?
• Erysipelothrix infections in humans characteristically produce pathology at which site?
• Serratia species are unique in the Enterobacteriaceae by producing which extracellular hydrolytic enzyme?
• In an anaerobic culture, olive-green to black colonies consisting of gram-positive cocci most likely represent which organism?
• Bacteria producing carbapenemase would be expected to be resistant to which class of antibiotics?
• Woman returns from Mexico after consuming unpasteurized cheese; most likely etiologic agent?
• Which one of the following drugs is considered as primary antimycobacterial therapy?
• Which characteristic is true for Clostridium tetani?
• An anaerobic, gram-negative rod can be presumptively identified by Gram stain morphology and inhibition by bile and a 1-μg kanamycin disk. Which organism is this?
• Which spirochete is known for causing epidemic relapsing fever?
• Which organism is the most common cause of pneumonia in elderly patients?
• Which organism is often implicated in food poisoning and belongs to the Bacillus genus?
• Brill-Zinsser disease is a recrudescent form of infection with which agent?
• Explosive watery diarrhea with severe abdominal pain after eating raw shellfish is most characteristic of infection caused by which organism?
• The anaerobic, gram-negative, curved, motile bacilli associated with bacterial vaginosis belong to which genus?
• In legionellosis, which clinical presentation can occur?
• Which organism is the leading cause of keratitis in contact lens wearers?
• Traveler's diarrhea is most commonly associated with which organism?
• Which is the characteristic colony description of Corynebacterium diphtheriae on Tinsdale agar?
• An example of an oxidase-positive, glucose nonfermenting organism is
• Which reaction is typical for Escherichia coli?
• Which test is most appropriate for presumptive identification of Clostridium perfringens?
• Which statement is true of Clostridium tetani?
• Which Legionella species is positive for hippurate hydrolysis?
• Which antimicrobial acts by inhibiting cell wall synthesis?